2011-01-13_REVISION - C1981038 (8)

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The geotechnical specifications are found in Volume 6, prepared by Golder Associates, consultant to the operator. This appendix presents the results of geotechnical investigations, stability analyses and detailed engineering design for the portal bench cut and fill and the accompanying haul road. The stability analyses are based upon projected cut slope configurations and material mechanical properties obtained from material sampling and laboratory analyses. Stability analyses were completed for cross sections chosen at road stations believed to represent potentially critical slope stability situations along the proposed upgraded haul road. As a result of this slope stability analysis, the operator amended its original proposed road cut slope configurations to use a Hilfiker wall, or equivalent, retention system. The retention system will be utilized as depicted on Sheet 7 of 10 of the Golder Associates report, entitled "Haul Road (1)," to reduce the unretained cut slope heights to a maximum of 30 feet. The Hilfiker treatment will be applied between road design stations 29+50' and 36+50'. Unretained cut slopes will not exceed a maximum slope gradient of 1.25h: 1.0v (horizontal to vertical) unless an appropriate slope stability monitoring program has been approved by the Division. With an approved monitoring program, cut slopes will be allowed to reach a maximum slope gradient of 1.0h: 1.0v (horizontal to vertical). The stability analysis determined a minimum operational static slope safety factor adjoining the upgraded haul road of 1.72. As required in the approved reclamation plan, the operator removed and reclaimed that portion of the haul road constructed to connect the existing public access road to the proposed portal bench embankment across East Roatcap Creek (design plan road Station 32+50' to 38+50'). The ford of an ephemeral stream with a watershed of at least one square mile was approved by the Division since it would not seriously alter normal water flow, contribute to sediment load, or cause adverse affects to fish or wildlife. The ford is located on East Roatcap Creek where the BLM road, used to access the West Mine fan facilities, crosses this creek. The R.O.M. stockpile haul road was constructed between May 10, 1976 and May 4, 1977. Minor Revision No. 66 formally included this haul road into the permit application. The road had been constructed on mainly fill material. It was surface treated with 12 inches of gravel in June of 1992 gravel and certified. A portion of the road was reclaimed when the R.O.M. area was reclaimed. The remaining portion of the R.O.M. haul road will be reclaimed as well. The haul road leading to the West Ridge Waste Pile was constructed in 1984 and had originally been designated as an access road. However, the road was upgraded to a haul road and a certified relevant showing, pursuant to Rule 4.03. 1 (1)(d)(ii) was submitted as part of the permit renewal no. 3 adequacy. The certification states that, with the information that is available, the haul road meets the specifications of Rule 4.03.1, except for grade requirements. The 400 feet of road has an overall grade of 12.5 percent, in exceedence of the 10 percent upper limit for overall grade, as required in Rule 4.03.1(3)(a)(i) and in exceedence of the maximum grade of 10 percent for any 300 foot section within any 1000 foot length, as required in Rule 4.03.1(3)(a)(iii). The Division granted BRL's request to accept this alternative design, as allowed in Rule 4.03.1(1)(e), based on the performance history of this road over the years. II. Support Facilities - Rule 4.04 The mine facilities at the Bowie No. 1 Mine were predominately located in three areas - the main East Mine and the run-of mine (ROM) stockpile area across the way on Steven's Gulch road, the Bowie No. 1 West Mine and the train loadout. Three other miscellaneous structures are found within the permit area. They include the guard shack at the entrance to the East Mine 24